Heretofore, there is known in the prior art of a plug-in fuse carrier operable as a surge-current protector for the cross-connection of two rows of terminals of a telephone terminal block, referred to as an AT&T Style 110 Block, and in common use in telephone and other electronic applications. Such a fuse carrier is illustrated and described in U.S. Pat. No. 4,968,264 to William E. Ruehl et al., which is assigned to the same assignee as the present invention. The fuse carrier is formed of an insulating housing 12 and a cover 14 mounted on the housing. The cover 14 includes a first platform 16 disposed at its one end and a second platform 18 disposed at its other end. The cover is positioned on the housing so as to enclose a cavity 20 in the housing. Fuses 22 and 24 of a tubular configuration are off-set mounted in the cavity so as to accommodate their protruding diameters and to minimize the space requirement within the cavity 20. Each of the fuses includes contact blades 32, 36 extending through aligned slits in the housing end walls for resting against an upright 88 and for providing a contact area in a gap 86 at each end of the fuse carrier. The fuse carrier is readily insertable between the two rows of the terminals of the terminal block so as to connect two circuits with the fuses 22, 24.
Accordingly, this prior art fuse carrier only provided for surge-current protection. However, it is also generally known that telephone circuits operate on relatively low voltages and are sometimes exposed to transient voltages of considerably higher levels than the normal operating voltages. This may be effected by a lightening strike, by a short circuit with a high voltage line, and by other causes. Therefore, it is also desirable to provide high transient voltage protection for the telephone circuitry.
While there are also known in the prior art of plug-in structures for use with telephone terminal blocks so as to provide connection thereto, including electrical components for protecting against high transient voltages, the present invention represents additional improvements over the prior art transient voltage protectors and the surge-current protector described in connection with the '264 patent.
Specifically, the present invention provides a voltage protector and grounding bar arrangement for use with a telephone terminal block which includes a two-piece interfitting housing for receiving an overvoltage protection device having a ground contact. A strip-like grounding bar has been designed for mounting into an existing unused opening appearing between two rows of terminals in the telephone terminal block and for connection to the ground contact. Further, the housing is of a unique construction for connecting the overvoltage protection device across opposed terminal pairs in the two rows of terminals in the telephone terminal block. The housing is also adapted to receive and connect a plug-in surge-current protector into the circuit.